The invention in general relates to skylight constructions used in buildings to provide daylight and more particularly concerns a skylight construction that is highly energy efficient while at the same time meets safety and quality requirements of both local and federal regulations.
Basically a skylight permits one to substitute daylight for electric light in a building. This obviously can provide a savings in lighting costs, however with conventional skylight designs this savings can be more than offset by increased heating costs due to thermal energy losses through the skylight. The current high cost of energy makes it very important to consider the overall energy balance of skylights. A recent study by the University of New Hampshire has indicated that in order for a skylight to consume less energy than the roof deck it replaces it must include (1) insulation in the curbing on which the skylight rests which approaches the effectiveness of the insulation of the roof, and (2) air infiltration approaching zero. Meeting such objectives in the design of skylights is not easy because skylights must also meet criteria for fire-resistance, shape, strength etc. imposed by federal and local regulations and functional requirements. For example urethane foam is an effective insulating material which because of low cost and rigidity lends itself to the construction of the curbing to which the skylight cover and frame is secured. However urethane foam also is a fire hazard, and therefore regulations require that it must be covered with a material such as aluminum; aluminum however, is thermally very conductive. Further, molded structural foams which are "self skinning" (i.e. no metal skin is required) have such high densities that they offer very poor resistance to heat loss, and they present a fire hazard. Other design materials that might theoretically solve the heating loss problem within the limitations set by the building codes are prohibitively expensive. Thus although energy efficiency has been a goal of skylight design for many years, until now competitive skylight constructions have not successfully solved the problem.
Accordingly it is an object of this invention to provide an improved skylight construction that overcomes one or more disadvantages of conventional skylight constructions.
It is a further object of this invention to achieve the preceding object with a skylight construction that is relatively energy efficient compared to conventional skylight constructions.
It is a further object of this invention to achieve one or more of the preceding objects in a skylight construction in which the curb insulation is nearly as effective as the insulation of the roof.
It is a further object of this invention to achieve one or more of the preceding objects in a skylight construction which reduces air infiltration nearly to zero.
It is another object of this invention to achieve one or more of the preceding objects with a skylight construction that meets code requirements for fire resistance.
It is a further object of this invention to achieve one or more of the preceding objects with a skylight construction that meets code requirements of shape, strength and like qualities.
It is a further object of this invention to achieve one or more of the preceding objects with a skylight construction that meets functional quality requirements.
It is a further object of this invention to achieve one or more of the preceding objects with a skylight construction that has a pleasing appearance.
It is a further object of this invention to achieve one or more of the preceding objects with a skylight construction that can be produced at a competitive price.